Just got a load of Oaxaca from a friend who picked it up at a plantation in Mexico. He has family from Mexico.

This bean is as yellow as Monsooned Malibar, big and very light volumed. Looks dried out. I'm assuming it's dry processed.

Roasts normally. Brews a very, very good vacuum press.

Trouble is on the grind. I roast just touching 2nd crack and there's a good rolling 1st so there's no stall. Almost no chaff at finish. When grinding there's bits of skin or chaff all through the coffee. I can't use it for espresso because that skin/chaff causes severe channeling.

Is this normal of dry processed Oaxaca? What is this chaff stuff and can anything be done to screen it out of the grind?

Thanks. Next time I grind some I'll include pictures.

This is a pic of the bean. The Oaxaca is on the right and a Mexican HG is on the left. Both are 25g samples.

Looks like some bad greens intermixed in there. Those dark black beans should be culled out prior to roasting. I have had some pretty funky looking beans that made super cups, the 07 aged Sumatra Lintong being one of them. They look like a cinnamon roast when green but make super coffee; Yemen greens also have a tan appearance and irregular shape. I would not worry about it. if they were old and baggy tasting, or had a fermented twinge to it I would worry but if the cup is good, drink away.

Chaff, normal for a dry processed coffee (even a wet but you get more in dry processed). Try putting your beans in a colander once roasted and gently toss them while blowing, I do it while the beans are in the cooling tray after the cooling cycle has completed. The chaff will blow out but it does no real harm to the cup unless present in huge quantities.

Thanks Dave,

I'm using a Hottop roaster that's normally does a good pulling out the chaff. This Oaxaca roasts with almost no chaff. Short of rolling the roasted bean around to maybe break off whatever chaff/skin doesn't peel off during the roast I wonder if there's anything else that can be done.

I included the defective beans as an example of what the batch looks like. From what I understand dry processing is a pretty hands on method. There's no water for the bad beans to float up on to screen themselves out. Screening has to be done by hand.

This is what the grind looks like- you can see the skin. It's not stray chaff that didn't get screened out.



This is what the roast looks like.

Boy, that actually looks like coffee in parchment, which is how it's often stored before being milled for shipment. If you take a handful of the greens, and rub them vigorously between your palms, does any of it break open? If it does, you're in for kind of a lot of work but the coffee will be fine. Inside the parchment is the silverskin (i.e. chaff after it's roasted), and inside that is the bean.

Best,
David

Thanks, David.

That's very helpful. Yes, if rub the green around it wants to break apart and, like you say, there's a silverskin inside. So it's the parchment that's still on the beans? Makes sense.

So, if I got it right, the parchment is light and accounts for the greater size of the green beans relative to other greens. The parchment is confining the chaff as well during roasting, I imagine. When ground after roasted it's both the parchment and the chaff that didn't get a chance to shed off during roasting that's accounting for all that skin.

Next time I roast I'll rub up the greens and see what happens.

Thanks again.

An update to the Oaxaca. Looks like David was right. I spent quite some time rubbing off the parchment from the bean to get about a 225g measure to roast on the Hottop.

This is the green free of parchment and the pile of parchment.



The bean roasted well. Lots of chaff. Looks pretty good. Just touching 2nd crack.



Thanks again for all the help. I'll let the roast rest a bit before trying it out for drip and espresso.